But for all its associations with Trump voters, the mood appears to have spread over the last two years. In a series of competitive congressional districts where The New York Times has been polling the midterm electorate, nearly half of Democrats say they feel this way — slightly more than among Republicans.

The seven districts that we’ve polled on that question — talking to 3,555 likely voters in California, Illinois, Kentucky, Minnesota and West Virginia — are not representative of the entire country. But they contain communities that are pulling ahead in America and those that are falling behind, as well as places that mirror the nation’s demographic future and its past.

The findings echo other polling on the question since Mr. Trump’s election. And together, the results suggest a rare political moment when Americans on all sides worry that they don’t recognize what the country is becoming.

“Normally, even in a politically polarized society, one side wins and they’re content,” said Stephanie McCurry, a historian at Columbia University. “It’s the other side that feels shut out of power.”

The moment now reminds her of the 1850s, when Northerners and Southerners were locked in a morally imbued fight over the nature of American values — and whether America was at its core a slave-owning society. Many Northerners were horrified by the 1857 Dred Scott decision, which effectively declared the United States such a place. Southerners were horrified by Northerners’ reaction to it, Ms. McCurry said.

“At that point, what you’re looking at is this sense of powerlessness all around about the ability of any institution to mediate not just a political conflict, but a conflict of fundamental values,” she said. “That’s maybe something like what we’re dealing with right now.”

The Senate’s rancorous fight over Judge Brett Kavanaugh’s confirmation, she added, has similarly added to pessimism about resolving these conflicts.

In the two years since Mr. Trump’s election, protesters and politicians on the left have lamented the erosion of values around tolerance and diversity. On the right, they have continued to mourn the loss of religious and traditional family values at the center of American life.

Ms. Hochschild identifies as a liberal herself, and after Mr. Trump’s election, she said one of the conservative voters she described in her book sent her an email.

“She said, ‘Well, I guess it’s now your time to feel like a stranger in your own land,’ ” Ms. Hochschild said. She acknowledges that she has felt this way of late, as she has watched President Trump declare the free press the enemy of the people and question the independence of the judiciary. “I had no idea we could come this far this fast and challenge things I thought were basic,” she said. “It feels like some pillars of our culture are being shaken, stress-tested.”

That is precisely the feeling she had described in Louisiana.

On other survey questions, Democrats and Republicans sometimes swap views depending on which party is in power. Republicans, for example, have become much more upbeat about the economy and their own finances, and Democrats less so, since Mr. Trump took office.

But it does not seem, with Mr. Trump in power, that partisans have simply traded views on who feels estranged. And that is part of what makes this moment unusual. Even as the Trump presidency has troubled Americans who didn’t vote for him, the president has continued to repeat the messages that helped him appeal to disaffected voters in the first place. And he has told his voters that he and they have not been accepted by institutions like the news media, the entertainment industry, academia and even some of corporate America.

“Trump is continually stoking these feelings of resentment, of loss,” said Daniel Cox, the research director with the Public Religion Research Institute. “If you’re already primed to feel that way, getting a sort of regular dose of that kind of rhetoric I think would cause you to continue to believe it.”

P.R.R.I. surveyed people about whether they felt like strangers in their own country shortly before the 2016 election, and again in 2017. The share of white men with no college degree saying this didn’t decline as a result of Mr. Trump’s election — it inched up to 49 percent from 48 percent.

The share of African-Americans saying the same rose to 59 percent from 48 percent (almost identical to what Times polls have found). Mr. Cox suggests, though, that while this sense of estrangement has been politically valuable to Mr. Trump in animating Republican voters, the same probably won’t be true for Democrats. Feelings of loss on the left — a weakening of values around voting rights, abortion rights, LGBT tolerance — aren’t as easily bound together in a singular cultural narrative.

The fact that “feeling like a stranger in your own land” can encompass all of these values is part of what makes it a powerful indicator of the American mood. The idea touches something more fundamental than policy preferences, more personal than how people view individual leaders.

“This does get at something a little bit deeper, that ‘I’m really troubled by — insert your own thing,’ ” said Patrick Ruffini, a Republican pollster. “ ‘I’m troubled by these political divisions, I’m troubled by how things are going culturally, I’m troubled by crime and the lack of moral fiber.’ I don’t think this sort of limits you.”

There may even be something hopeful in the fact that many Americans are deeply troubled about something — if not the same thing.

“It is evidence of a healthy process,” said Heather Cox Richardson, a historian at Boston College. In the 1850s and the 1920s, she said, similar moments of widespread disaffection and anger with powerful elites led to broad grass-roots movements that gave way, in their time, to the birth of the Republican Party and later the election of Franklin Delano Roosevelt. “It is also evidence,” she said, “of an exceedingly dangerous process for the people who are in power.”

Nate Cohn contributed research.

Emily Badger writes about cities and urban policy for The Upshot from the San Francisco bureau. She's particularly interested in housing, transportation and inequality — and how they're all connected. She joined The Times in 2016 from The Washington Post. @emilymbadger

A version of this article appears in print on , on Page A22 of the New York edition with the headline: Estranged in America: Both Sides Feel Lost and Left Out. Order Reprints | Today’s Paper | Subscribe